First understand that dimmers will normally hum - usually worse at low dim settings. The fixtuer itself will also him - I am presuming this is an incandescent bulb fixture. Dimmers wont work on CFL (Fluorescent) style bulbs.
Knowing this expect some hum. You have 15 bulbs each at 60 watts each. THis totals 900 watts - a pretty significant draw on the power for any lamp. the 900 wats represents about 8+ amps of current at 120 Volts AC. This in itself should no be a problem on a typical electrical circuit.. Most such circuits are fused OR circuit breaker protected to at least 15 amps. Some older homes (IE pre1960s or such) may even hqve only 10 amp protection so FIRST - check the fuse or breaker rating - is it 15 amps min. Most circuits for lighting are 15 amps in newer homes. MOST other power circuits with outlets on them (perhaps with lighting in the circuit) may be even 20 to 25 amp fused - so first of all - verify that the circuit is at least 15 and preferrably 20 amps in the fuse (breaker) box). Ifthis is true then the 8+ amp draw from this lighting load is not the ONLY thing popping that fuse (breaker). It is likely that there are other items on that same circuit loading it beyond capacity. The light intself presents a significant load and hence could simply be sucking current beyond the fuse limits. example - this lighting fixture will draw 8 amps when on. Lets say those wires in the wall go to perhaps a couple other light fixtures - maybe a bath ceiling fan and maybe the outside front lights. Lets say the outside lights draw 240 wats or 2 amps - and the bath fan draws 2 amps and - wall outlet on that same circuit draws 6 amps with the TV, DVD, Audion system etc on. thats 2 + 2 + 6 or 10 amps and if you turn on this lighting fixture you draw another 8 amps which totals 18 amps. If this is a 15 amp circuit that fuse would likely blow. So check the overall load. YOu can do this by turning on evey light and appliance (TV et al) and then unscrewing the fuse or flipping the breaker - then tour the house and make a note of what turned off. Write down the location -name of the item and wattage noted on that item. Total it up and make a note that "Breaker 2 goes to x,Y,Z etc" for future ref. When you find the breaker for this particular 900W lighting fixture note all the items that shut off. I would even take a small lamp and check each outlet on every wall and see if it is dead and note those too. Most houses esp older ones are very underwired and circuits typically have too many things on one circuit. If you find this lighting fixture is on an overloaded circuit you have a couple choices. One is to rewire (run new leads) to that light and add a new circuit or reroute other wires on that circuit to another fuse. Unless you are very handy - this is job for an electrician.
ALso note that most std dimmers are rated for 600 watts max. YOu are well in excess of that here for that fixture. If you go to an electrical supplier they have higher power rated dimmers that will fit in standard boxes. Get one reated at least to 1000 watts. Normally these arent available at home supply stores but you can check at Home Depot or Lowes or similar stores. They MAY have them. Look on the package -the max rating is always printed on there. Use nothing under 1000 watts.
This should solve your problem. Good quality dimmers will work well -not hum - even at low levels usually -but some hum might occur and the bulbs you use make a difference if that is what is "singing". Try different bulbs at low dim setting till you find one.Bulbs all have different filament supports in them and that is what affects singing themost. So buy an assortment and try 2 or 3 at a time. THis might cost a few bucks up front - but 15 bulbs singing canbe a nuisance. So I would try this first.
Marty
